(defun insert-balanced-comments (arg)
  "Insert a set of Common Lisp balanced comments
around the s-expression containing point.  If this command is invoked
repeatedly (without any other command occurring between invocations),
the comment region progressively moves outward over enclosing
expressions."
  (interactive "*p")
  (save-excursion
    (when (eq last-command this-command)
      (when (search-backward "#|" nil t)
	(save-excursion
	  (delete-char 2)
	  (while (and (< (point) (point-max)) (not (looking-at " *|#")))
	    (forward-sexp))
	  (replace-match ""))))
    (while (> arg 0)
      (backward-char 1)
      (cond ((looking-at ")") (incf arg))
	    ((looking-at "(") (decf arg))))
    (insert "#|")
    (forward-sexp)
    (insert "|#")))

(defun remove-balanced-comments ()
  "Remove a set of Common Lisp balanced comments enclosing point."
  (interactive "*")
  (save-excursion
    (when (search-backward "#|" nil t)
      (delete-char 2)
      (while (and (< (point) (point-max)) (not (looking-at " *|#")))
	(forward-sexp))
      (replace-match ""))))